1. Field of the Invention
The present invention relates to an adjustment mechanism adjusting the tilt angle in a compact disc recording/reproducing device, particularly to an adjustment mechanism for use in a compact disc recording/reproducing device of high precision for data of high density.
2. Description of Related Art
On a disc, signals are stored in units that are either 0 or 1. The signals are read by measuring the intensity of a laser beam reflected on a reflective layer on the disc and by subsequent decoding.
A conventional optical reading system for a disc is shown in FIGS. 9 and 10. A pick-up head 1 is sliding along a guiding rod 2 and a guiding rail 3, which are mounted on a base 4. A motor 5 drives the pick-up head along the guiding rod 3, so as to scan the disc and read data. The disc is set on a turntable 6, which is driven by a spindle motor.
As shown in FIGS. 10-12, the guiding rail 3 and the base 4 are made by injection die casting. The guiding rod 2 has two ends, which are laid into accommodating parts 7 and 8, respectively, one end being fixed to a metal plate 9A by a screw 9. Due to production and assembly defects, the positions of the ends 7,8 and the guiding rail 3 are often different from the design, causing the angle of incidence of the laser beam on the disc, which is defined as tilt angle, to deviate from the intended value, as well. Reading errors result. This problem becomes more severe, as the data density on CDs increases.